Deposition of metal films and clusters by reactions of compounds with low energy electrons on surfaces

Abstract

A thin film of material such as metal is deposited on the surface of a substrate by placing a substrate (22) into a chamber (10) containing holder (12) cooled by heat exchanger 18. A beam (56) of U.V. light from the illumination source (42) is projected through monochromator (43), mask (46) and lens (16) onto a selected area (58) of the substrate at an energy level exceeding the photoemission threshold of the surface. A slow electron (60) is ejected from the surface into the capture zone (62). A compound AB such as iron pentacarbonyl from supply (30) is leaked into the chamber (10), enters the capture zone (60) to form a highly reactive deposition fragment A- which attaches to the surface and a dissociation fragment which is evacuated through outlet (14). The deposited fragment may further dissociate to form metal deposit.

What is claimed is: 
     
       1. A method for depositing a thin film on the surface of a substrate comprising the steps of: placing said substrate in a deposition zone;   introducing a first precursor gas containing a first compound capable of electron capture dissociation into said deposition zone;   generating low energy electrons at or near the surface of said substrate;   dissociatively capturing said electrons with said first compound resulting in dissociation of said first compound into a coordinately unsaturated negatively charged reactive first deposition species and a first dissociation species;   depositing said first deposition species on the surface of said substrate; and   removing said first dissociation species from said deposition zone.   
     
     
       2. The method according to claim 1 wherein said first precursor gas contains a first compound which undergoes dissociative electron capture with electrons of near thermal energies. 
     
     
       3. The method according to claim 2 wherein said first compound is an organometallic compound. 
     
     
       4. The method according to claim 1 wherein said substrate is selected from the group consisting of glass, metal or silicon. 
     
     
       5. The method of claim 3 wherein said organometallic compound is a metal carbonyl which dissociates by electron capture to form a negatively charged unsaturated metal carbonyl first deposition species and a carbonyl first dissociation species. 
     
     
       6. The method according to claim 1 wherein said deposition method is carried out in said deposition zone under vacuum less than atmospheric pressure and at a temperature below room temperature. 
     
     
       7. The method according to claim 1 which includes the additional steps of: introducing a second precursor gas containing a second compound capable of electron capture dissociation into deposition communication with said first deposited species;   irradiating said first deposited species and substrates with radiation of an energy sufficient to eject low energy electrons from said first deposited species but not from said substrate;   dissociatively capturing the electrons ejected from said first deposited species resulting in dissociation of said second compound into a coordinately unsaturated negatively charged reactive second deposition species and a second dissociation species; and   depositing the second deposition species on said first deposited species.   
     
     
       8. The method according to claim 7 wherein said deposition method is carried out in said deposition zone under a vacuum at cryogenic temperatures. 
     
     
       9. The method according to claim 7 wherein said second compound is an organometallic compound which dissociatively decomposes into a negatively charged metallic second deposition species and an organic second dissociation species. 
     
     
       10. A method for depositing a thin film on the surface of a substrate comprising the steps of: placing said substrate in a deposition zone;   introducing a first precursor gas containing a first compound capable of electron capture dissociation into said deposition zone;   generating a pattern of low energy electrons at or near the surface of said substrate;   dissociatively capturing said electrons with said first compound precursor gas resulting in electron capture dissociation of said first compound into a coordinately unsaturated negatively charged reactive first deposition species and a first dissociation species; and   depositing said first deposition species on said surface of said substrate in the pattern defined by said generated low energy photoelectrons.   
     
     
       11. The method according to claim 10 wherein said first precursor gas contains a first compound which undergoes dissociative electron capture with electrons of near thermal energies. 
     
     
       12. The method according to claim 11 wherein said first compound is an organometallic compound. 
     
     
       13. The method according to claim 10 wherein said substrate is selected from the group consisting of glass, metal or silicon. 
     
     
       14. The method of claim 11 wherein said organometallic compound is a metal carbonyl which dissociates by electron capture to form an unsaturated negatively charged metal carbonyl first deposition species and a carbonyl first dissociation species. 
     
     
       15. The method according to claim 10 wherein said deposition method is carried out in said deposition zone under vacuum at cryogenic temperatures. 
     
     
       16. The method according to claim 10 which includes the additional steps of: introducing a second precursor gas containing a second compound capable of electron capture dissociation into communication with said first deposition species deposited on the substrate surface;   irradiating said deposited first deposition species and substrate with radiation of an energy sufficient to eject low energy photoelectrons from said deposited first deposition species but not from said substrate;   dissociatively capturing the photoelectrons ejected from said deposited first deposition resulting in dissociation of said second into a coordinately unsaturated negatively charged reactive second deposition species and a second dissociation species; and   depositing the second deposition species on said deposited first deposition species.   
     
     
       17. The method according to claim 16 wherein said deposition method is carried-out in said deposition zone under a vacuum at cryogenic temperatures. 
     
     
       18. The method according to claim 16 wherein said second compound is an organometallic compound which decomposes into a negatively charged metallic second deposition species and a volatile organic second dissociation species.